What is the difference between Finalize and Dispose in .NET?

Finalize is called by the garbage collector for cleanup, while Dispose is explicitly called to release unmanaged resources deterministically.

Which is preferred in modern .NET: Dispose or Finalize?

Dispose is preferred because it allows developers to clean up resources immediately and avoid relying on the garbage collector.

Use of Finalize vs Dispose in .NET

💡 Concept Name

Finalize vs Dispose in .NET

💡 Concept: Finalize vs Dispose

Finalize and Dispose are both about cleaning up unmanaged resources in .NET, but they work very differently. Understanding when and how to use them is key for writing memory-safe code.

📘 Quick Intro

In .NET, most memory is managed automatically by the garbage collector. But for unmanaged resources (like file handles, sockets, or database connections), you must clean them up yourself. - Finalize() is called by the GC as a fallback. - Dispose() is called directly by the developer for predictable cleanup.

🧠 Analogy

Think of checking out from a hotel: - If you leave the room messy and wait for housekeeping to clean it up later → Finalize. - If you tidy up yourself before leaving → Dispose. Dispose gives you control, avoids delays, and is more polite to the system.

🎯 Purpose & Use Case

✅ Use Dispose() for immediate, controlled cleanup
✅ Use Finalize() only when unmanaged resources must have a fallback release
✅ Combine them using the Dispose Pattern
✅ Always wrap IDisposable objects in using blocks for safer code

💻 Real Code Example

public class FileManager : IDisposable
{
    private FileStream _stream;

    public FileManager(string path)
    {
        _stream = new FileStream(path, FileMode.Open);
    }

    public void Dispose()
    {
        _stream?.Dispose();
        GC.SuppressFinalize(this); // avoid finalizer call
    }

    ~FileManager()
    {
        Dispose();
    }
}

❓ Interview Q&A

Q1: What is Finalize() used for?
A: Cleanup of unmanaged resources during garbage collection.

Q2: What is Dispose() used for?
A: Manual cleanup of unmanaged resources.

Q3: Which one is deterministic — Finalize or Dispose?
A: Dispose.

Q4: What does GC.SuppressFinalize() do?
A: Prevents the Finalize call for an object.

Q5: Can we override Dispose()?
A: Yes, in classes implementing IDisposable.

Q6: When is Finalize called?
A: By GC before reclaiming memory.

Q7: What pattern uses both Finalize and Dispose?
A: Dispose Pattern.

Q8: Why prefer Dispose over Finalize?
A: For performance and control.

Q9: Should Dispose call GC.SuppressFinalize?
A: Yes, if Finalize is also implemented.

Q10: Can we use using() with Finalize?
A: No, only with IDisposable/Dispose.

📝 MCQs

Q1. Which method is called by the garbage collector?

Dispose
Free
Release
Finalize

Q2. Which method must be called manually?

Finalize
Collect
Dispose
CleanUp

Q3. What interface must a class implement to support Dispose()?

IGC
IReleasable
IDisposable
IManualCleanup

Q4. Which method is deterministic?

Finalize
Dispose
Both
None

Q5. Which method is safe to use in using() block?

Dispose
Finalize
Close
Abort

Q6. What does GC.SuppressFinalize() do?

Forces GC
Delays finalizer
Prevents GC from calling Finalize
Removes IDisposable

Q7. When should Finalize() be used?

Always
Never
Only with IDisposable
When unmanaged resources need fallback cleanup

Q8. What is the best practice for unmanaged resources?

Only Finalize
Only Dispose
No cleanup needed
Implement Dispose and optionally Finalize

Q9. Is Dispose() called automatically?

Yes
No
Only with GC
Only on crash

Q10. Which causes a performance hit if not suppressed?

Dispose
using()
GC.Collect()
Finalize

💡 Bonus Insight

Think of Finalize as a safety net — useful, but not the main tool. In production-quality .NET apps, you’ll almost always use IDisposable + using and rarely ever touch Finalize directly. Clean resource management = fewer leaks and better performance.